1. Field of the Invention
This invention relates to a novel cam arrangement which includes a cam means and a support means. More specifically, this invention relates to such an arrangement in which the cam means is movable, to a controlled extent, relative to the support means.
This invention also relates to a coffee brewer using the novel cam means and support arrangement.
2. Discussion of the Prior Art
Cam and support means, such as sprocketed arrangements are well known in the art. For the most part, the cams have a peripheral side surface, on which a roller can roll. The cross-sectional shape of the peripheral surface includes a portion which is substantially a semicircle. One end of the semicircle is joined to a substantially straight inwardly directed line, and the other end of the straight line is joined, by a smooth continuation, to the other end of the semicircle.
In the operation of the cam arrangement, the roller is displaced along the peripheral surface of the cam, either by movement of the cam or by movement of the roller. The direction of motion of the roller is from the smooth portion towards the straight line portion over the semicircular portion. There is an abrupt change of direction of motion of the roller when the roller passes the end of the semicircular portion and engages the straight line portion. The abrupt change of motion is used to initiate a change in condition or the starting or stopping of an activity.
Although the change of motion is abrupt, it is far from instantaneous as the roller must roll over the edge of the surface joining the end of the semicircle with the straight line portion, and for some purposes, the time consumed in the rolling over the edge makes the reaction time of the cam arrangement too slow.
One of the areas in which the cam arrangement is too slow is in a coffee brewing machine of the type described in U.S. Pat. No. 3,565,641, King, issued Feb. 23, 1971, and assigned to the assignee herein (incorporated herein by reference). In this machine, a brewing chamber, in the form of a cylinder, is disposed on top of a second chamber, also cylindrical. The floor of the brewing chamber comprises a filter paper which is moved on a roll to present a clean portion for each new cup of coffee to be brewed. After the coffee is brewed in the brewing chamber, and then expelled therefrom, a residue of coffee grounds remains on the filter surface.
When the brewing process is complete, the brewing chamber is lifted vertically upward, and the filter paper is moved on its roll to remove the used filter sheet, along with the residue of coffee grounds, away from the brewing area, and to place a fresh sheet of filter paper in the brewing area. The timing of the lifting of the brewing chamber and the start of movement of the filter roll is governed by a cam and roller arrangement, and, for many reasons, the same motor which drives the cam also drives the filter roll.
With the above-described arrangement, there is the problem that the roll of filter paper begins to move before the brewing chamber is completely lifted. Accordingly, some coffee grounds on the used filter may be caught by the bottom of the brewing chamber, and they may remain stuck to the brewing chamber.
The action of lifting of the brewing chamber is initiated when the roller of the cam and roller arrangement engages the straight line portion, and the slowness of the lifting is due to the slow speed of the cam, and the radius of the roller.